Question

find the nth partial sum of the arithmetic sequence:
1.50, 1.45, 1.40, 1.35 . . . n=20

Answer 1

http://www4c.wolframalpha.com/Calculate/MSP/MSP53231a0e526h2h925c3f00001g56fgg26cchdea0?MSPStoreType=image/gif&s=43&w=483&h=18

Answer 2

how do i figure it out???

Answer 3

I send you the link it should be there

Answer 4

what link

Answer 5

It's just arithmetic, don't use "partial Sum" it confused the solvers:
a20 = a1 + ( n -2) d
= 1.5 + ( 19 ) .5 = 11

Answer 6

Just plug the number in, the formula in your hand already!